In a large pan, melt the butter over medium heat. Whisk in the flour to make a paste. Cook for a minute, while stirring, then slowly mix in the milk. Reduce heat to medium low and continue to cook, stirring, until the mixture has thickened.
Stir in the mashed sweet potatoes, salt, and nutmeg. Once heated through, stir in the maple pecan goat cheese and remove from heat. Transfer the mixture to an airtight container and refrigerate overnight.
Once the mixture is thoroughly chilled and thickened, fill a pot or deep fryer with 3-4 inches of vegetable oil. Heat the oil to 375˚F. Cover a plate with a towel and place nearby. In a shallow wide bowl, combine the breadcrumbs and pecans. In another bowl, beat together the eggs. Place a plate nearby.
Remove a tablespoon of the thickened filling and roll it into a ball. Coat thoroughly in the breadcrumbs, then the eggs, and again in the breadcrumbs. Place on a plate and repeat with another 4-5 pieces. Add to the heated oil and fry until golden, 3-4 minutes. Transfer to towel-lined plate and repeat with remaining filling.
In a small bowl, whisk together the dijon mustard and maple syrup. Serve immediately with the hot sweet potato maple pecan goat cheese croquettes.